The present invention relates to vehicle seat belts and more particularly to vehicle seat belt system having a diagonal belt element.
Conventional vehicle seat belt systems have an elongate belt that extends from an anchored emergency locking retractor above and to one side of the seat, the belt extending diagonally downward to a releasable lower anchor at an opposite side of the seat, thence across the seat to a permanent lower anchor on the same side as the retractor. Typically, the releasable anchor is slidably connected to the belt for automatic adjustment equalizing the belt tension on opposite sides of the releasable anchor.
A problem with these conventional seat belt systems is that the diagonal portion of the belt can be ineffective in restraining an occupant of the vehicle during a collision, particularly when a collision impact occurs at an oblique angle to a longitudinal axes of the vehicle. This problem is compounded in many larger vehicles wherein the retractor is located at door height some distance from both the back of the seat and an occupant's shoulder. A further problem is that upper body support with the conventional systems is diminished even more when the occupant is of less than average height and build.
A further development is the use of some form of connection to the diagonal belt portion between the retractor and the releasable anchor. See, for example, U.S. Pat. No. 3,860,261 to Takaba that discloses a floormounted retractor, the belt extending upwardly to an anchored roller, thence diagonally downwardly to the releasable anchor, the upwardly extending portion of the belt having a ring member fixed thereon and enclosing the diagonal portion at a point proximate the seat back. See also U.S. Pat. Nos. 4,236,755 to Pollitt et al., 4,243,266 to Anderson, and 4,289,352 to Ashworth, each disclosing an auxiliary belt that extends from the bottom of the seat back upwardly along the forward portion of the seat back to a point of attachment with the diagonal belt portion proximate the top of the seat back, the auxiliary belt extending over the top of the seat back to an attachment. Anderson and Pollitt et al. disclose the attachment of the auxiliary belt to an anchor for the upper retractor. Ashworth, on the other hand, has the auxiliary belt enclosing the seat back, its ends being connected together. However, the above-disclosed seat belt systems exhibit one or more of the following disadvantages:
1. The auxiliary belt passing along the front of the seat back is unsightly and dangerous in that a user's arm fingers or arm can be injured by being caught between the auxiliary belt and the seat back as the user is entering or leaving the vehicle;
2. They are ineffective that the diagonal belt portion is not adequately supported proximate the user's shoulder;
3. They are awkward in that they require difficult adjustments;
4. They are expensive to produce in that they require numerous connections and attachments; and
5. They are difficult to install, particularly as a retrofit to an existing system, because they require expensive disassembly of an existing system and/or modifications thereto that are not practical in the field.
Thus there is a need for a seat belt system that is effective in retaining a seated vehicle occupant in the event of a collision, whether straight on or at an oblique angle, that is inexpensive to produce as either a complete system or as a retrofit, and easy to both use and install.